NORTH COAST GARDENING: Freeze and frost are not the same

Since these past few mornings we have awakened early to find our gardens blanketed with a rime of frost, it comes as no surprise that potted plants are frozen ice pops. Water gardens are glazed in ice. Hoses have ruptured. The soil is hard as concrete. Early morning temperatures have dipped into the 20s for several days now.

Freeze has taken hold and it is only early December. Freezing weather could continue off and on until March. So, if you have a prized plant, such as a Meyer lemon, a favorite fuchsia or geranium, it is best to consider a permanent warm spot for the winter.

Tender plants especially suffer in extreme cold because freezing temperatures cause the water in plant cells to freeze, damaging the cell walls. Frost-damaged plants are a sad-looking lot; their growth becomes limp, blackened and distorted. Evergreen plants often turn brown and the leaves of tender plants take on a translucent appearance. They seem to melt.

Frost problems are often made worse where plants face the morning sun, as this causes them to defrost quickly, rupturing their cell walls.

Most local plants, even citrus, can take a bit of frost, but freeze is what actually kills.

Frost is when all through the night it is quite chilly, but not freezing, and then the temperature dips below 32 degrees F in the early morning, just before sunrise. This light frost happens all the time on the coast.

Freeze is when early evening temperatures dip below 32 and stay that way all night long. Water puddles are iced over in the morning; mud becomes frozen. Freeze.

Even hardy plants and tough evergreens can be damaged by prolonged spells of severe cold when soil becomes frozen. Roots are unable to take up water and plants can die from a lack of moisture.

Periods of cold, frosty weather during April and May can also kill blossoms and damage fruit.

When a favorite plant is damaged by a freeze, it is important to resist the temptation to cut back all the dead foliage immediately, unless you are planning on bringing it into a warmer, greenhouse situation. With established landscape plants, it is best to leave things as they are, because chances are good that down below the soil line the roots are okay. There may be little green buds lying low, waiting for the warmth of spring. This is especially true in coastal gardens. The damaged twigs and branches left intact will act as insulation when more cold weather occurs.

With inland gardens, tender plants not adequately protected already are probably goners. Looks like most of us will be making trips to the nursery next spring to replace what has already been lost.

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Terry Kramer is a trained horticulturist and journalist. She has been writing a garden column for the Times-Standard since 1982. To get in touch with Terry, send an e-mail to style@times-standard.com and put "For Terry Kramer" in the subject line, or write to Terry Kramer, c/o Times-Standard, P.O. Box 3580, Eureka, CA, 95502.